How to make it fully developable?

[jiangrm]

Tried to use only lines but it’s not right at in the middle. What can be done to make it fully developable? Thanks

 

 

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[Terrance Egolf]

Hello, Jiangrm.

A developable surface must continuously and smoothly curve in one direction, like the front and back halves of your vessel.

The reason the middle is not developable is that it contains a crease edge, which, by definition, has a discontinuous surface curvature. It’s a crease.

You can try removing the crease by selecting all the red edge segments there, then click on the Crease control in the Edge subgroup and see what that does. You may have to add some parallel Normal edges on both sides to smooth out the transition in that area.

Hope this helps.

Terry

[jiangrm]

Terrance Egolf wrote:

Hello, Jiangrm.

A developable surface must continuously and smoothly curve in one direction, like the front and back halves of your vessel.

The reason the middle is not developable is that it contains a crease edge, which, by definition, has a discontinuous surface curvature. It’s a crease.

You can try removing the crease by selecting all the red edge segments there, then click on the Crease control in the Edge subgroup and see what that does. You may have to add some parallel Normal edges on both sides to smooth out the transition in that area.

Hope this helps.

Terry

Thank you Terry. I realized that later, cut it in half and it looks good.

The other problem is I want to use a whole flat sheet to make the half hull. Is there any option to unfold it with the keel connected?

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[jiangrm]

Terrance Egolf wrote:

Hello, Jiangrm.

A developable surface must continuously and smoothly curve in one direction, like the front and back halves of your vessel.

The reason the middle is not developable is that it contains a crease edge, which, by definition, has a discontinuous surface curvature. It’s a crease.

You can try removing the crease by selecting all the red edge segments there, then click on the Crease control in the Edge subgroup and see what that does. You may have to add some parallel Normal edges on both sides to smooth out the transition in that area.

Hope this helps.

Terry

Removed crease of the edges in the middle, the whole hull turned red 😀

Well my goal is to develop a canoe hull that is fully developable. It looks seemingly possible with the paper model but I couldn’t prove/disprove it geologically. Is there any way to do that?

In any case if impossible, making hull in halfs is an acceptable compromise.

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[Terrance Egolf]

Yeah, well that didn’t work, did it? I was afraid that would happen.

You might consider a using a band of the appropriate width wrapped around the middle of the boat, which will be developable, with your two developable ends. You will have two crease edges this way, but it will look more like your paper conceptual model.

Another approach would be to use long strips the length of the hull, like planks, with creases between them. That involves a different construction method, however.

Terry

[Maarten]

As a consideration: your canoe design (with a smooth hull) can never be fully developable, as the surface curves in more than one direction (hence the red color in plate development). Not that it is impossible to create it from plates, but it will depend greatly on the properties of the plate.

If you want fully developable plates, consider making a lapstrake construction.

[jiangrm]

It will be a take-down lightweight canoe. In this case, my priority is material and simplicity of manufacturing. I wanted to use (ideally) a whole sheet of plastic film (very likely non-stretchable but possibly slightly stretchable) for the hull.

Taping it in the middle is ok but not preferable as it increased the risk of leak.

If calculating developability is possible from the curvature, is there any way to set developability as a constraint when moving the points around (like limiting the movement in one axis/plane)?

[Author]

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